Diaphragm fuel pump with vent



7, 1965 J. L. GRABIEL 3,200,758

DIAPHRAGM FUEL PUMP WITH VENT Filed Aug. 15, 1963 ATTORNEY United States Patent 3,200,758 DIAPHRAGM FUEL PUMP WITH VENT John L. Grahiel, Flint, Mich, assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware Filed Aug. 15, 1963, Ser. No. 302,277 10 Claims. (Cl. 103-150) This invention relates to pumps and more particularly to diaphragm type fuel pumps for serving internal combustion engines.

An automotive fuel pump is disclosed in the United States Patent 2,139,347 granted December 6, 1938 in the names of A. M. Babitch and G. W. Harry. That pump is provided with a pumping diaphragm actuated during the pumping stroke by a coil spring located in a spring chamber. The spring chamber wall has a vent or opening leading to the atmosphere to prevent a sealing diaphragm for a push rod from wearing out and to prevent loss of pump efficiency. Such a vent has become conventional in the field of automotive fuel pumps.

It has become desirable to improve the venting of the spring chambers in diaphragm type pumps. If a vent is made directly through the pump body wall as taught in the patent above referred to and particularly if it is made too large, foreign matter may enter the spring chamber and eventually adversely affect the oil seal diaphragm and the pumping diaphragm. Also, a too large vent allows noises produced by the pumping diaphragm, when stroking at peak pressures and vacuums, to escape from the pump. If a straightthrough vent is made too small, it would prevent the escape of noise but it would be so restrictive that there would be a loss in pump performance and the useful life of an oil seal around the conventional pumping diaphragm plunger as well as the life of the pumping diaphragm would be shortened.

An object of the present invention is to provide an improved diaphragm type pump in which a spring chamber is adequately vented without admitting foreign matter or emitting noises generated by pump operation.

To this end, a feature of the present invention is a pump body having a channel indirectly extending through the spring chamber wall of the body with the inside and outside ends of the channel angularly spaced about the axis of the pump or pump diaphragm.

This and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIGURE 1 is a sectional view through a fuel pump disclosed as an embodiment of the present invention, an engine camshaft drive for the pump also being shown in operative relation to the pump;

FIGURE 2 isa sectional view looking in the direction of the arrows 2-2 in FIGURE 1;

FIGURE 3 is a sectional view of a detail shown in FIGURE 1 and drawn to a larger scale;

FIGURE 4 is a view similar to that of FIGURE 3 but showing another form of vent channel and seal construction; and

FIGURE 5 is another view similar to that of FIGURE 3 but showing a third form of vent passage and seal construction.

The pump disclosed in the drawing includes a pump body generally indicated at and this body is in the form of two parts-a casting 12 and a sheet metal cover 14. The casting 10 bears a flange 16 which is adapted to be attached in a well known manner to the side of an internal combustion engine. The casting 10 is also recessed to form a spring chamber 18 and an L-shaped rocker arm chamber 20. The latter chamber is formed with an open end 22 adapted to be placed in communication with the ice interior of the engine being served and is fitted with a pin 24 about which a conventional rocker arm 26 is adapted to oscillate. In a typical engine installation one end 28 of the rocker arm is adapted to bear against one end of a rod 30 and the latter is conventionally held by a fixed bearing arrangement to reciprocate longitudinally and with its other end in constant contact with the peripheral surface of a cam 32 forming an integral part of an engine crankshaft 34. The other end 36 of the rocker arm 26 is notched to fit an annular member 38 which encircles the upper end of a diaphragm plunger or rod 40. The latter bears a head 42 and between the head 42 and the member 38 are two washers 44 and 46. The washer 46 forms a cushion to prevent noise. A coil spring 48 acts between the member 38 and an inside top surface 50 Within the casting 12 in such a way that the member 38 constantly acts on the end 36 of the rocker arm 26. This assures a constant engagement of the rod or plunger 30 with the cam 32 regardless of the variation in pump stroke length.

Surrounding the plunger 46 is a sheet metal annular member 52 which is made slidingly to receive the plunger and is also apertured as at 54. The member 52 bears an annular flange 56 so that the member is held in position with respect to the casting 12 by engagement with a rubber sealing means or diaphragm 58. The latter is flexible and is formed with a hub 60 engaging the rod 46 and adapted to move with the rod. A marginal. portion 62 of the sealing means 58 is frusto-conical and terminates in a peripheral flange 64. The latter is fixed in position between shoulder portions formed on the casting 12 and an annular sheet metal seal protector element 66.

A top peripheral flange 77 of the cover 14 is crimped about an annular rim 79 of the casting 12 with a pumping diaphragm 30 and a sheet metal member 82 interposed. The diaphragm is clamped between two metal protector plates 84 and 86 which are held together by means of annular members 88 and 90 retained on the lower end of the plunger 40.

The sheet metal element 82 is formed with a shallow recess 94 and a deeper recess 96. These are utilized to retain one way valve arrangements at 98 and 100 respectively. The valve arrangement 98 is similar to many now in use and comprises a movabl valve disk 102 held in position to close ports 103 by action of a spring 104. A space 108 in the cover 14 and surrounding the valve structures is in communication with an outlet tube 114. A much smaller space 112 beneath the inlet valve 100 and within the member 82 is in communication with an inlet tube 110.

The structure thus far described pertains mostly to details which are not essential insofar as the present invention is concerned and these details can be varied considerably without departing from the spirit of the present invention as will be seen as the description proceeds.

The present invention relates particularly to the means for venting the spring chamber 18. In this regard, the body casting 12 of FIGURES l to 3, inclusive, is shown to be provided with a channel 120. This channel is preferably made annular and forms a passage or vent extending indirectly with the aid of inside and outside openings through the Wall of the casting 12. The outside opening of the channel is shown at 122 and diagonally opposite to this opening and with respect to the pumping diaphragm 8t) and the plunger 40 is an inside opening 124. The latter is formed in the casting 12 so that it extends around the peripheral edge of the sheet metal member 66 to provide a connection from the spring chamber 18. Venting of the latter is by way of the opening 124 and then through the annular channel 120 to the outside opening 122. It will be noted that the channel 120 is largely spear es 3 defined by the casting 12. and partially by the flexible sealing means 58. A'liplZ overhangs the outside opening 122 to give additional protection against the admission of foreign matter and, conveniently, this lip is made due to a cast recess 128.

In the operation of the pump, the plunger 44 will be reciprocated by virtue of the action of the cam 32 and the spring 83. The sealing means or sealing diaphragm 58 will flex up and down with the plunger 40 and no stresses or strains will be placed on the diaphragm 58 because of the venting of the spring chamber 18 through the channel 120. The admission of dirt and the emission of noises are considerably reduced by virtue of the indirect path and also the length of the channel.

In FIGURE 4 an annular channel of a different form is shown. In addition, the push-rod sealing means is modified to include an annular and peripheral rib 142 adapted to be seated and held within a special recess 144 formed in the special pump casting 146. A special plunger 148 is used having a shoulder 159 to aid in the retention of a hub portion 152. of the flexible sealing diaphragm. In this case, a sheet metal shield 154 is used which has a trough-like periphery 156 cooperating with the inside surface of the wall of the casting 146 to define the annular channel 153. This channel has an outside opening as at 166 and the walls of a recess 162 protect or shield the latter. An inside opening is not disclosed in FIG. 4 but it will be appreciated that it may be similar to the opening 124 of FIGURE 1.

Another or third modification is depicted in FIGURE wherein a body casting 174 is recessed to hold the thickened periphery of a sealing member like in the case of FIGURE 4'but in this instance a shield 1'72 is made of different form to cooperate with the casting 176 in defining the arcuate or annular vent channel 174. As in FIGURE 4, the spring 83 is employed to hold the shield and sealing means in proper position with respect to the casting.

I claim:

1. A pump having a pumping diaphragm and a body enclosing a spring chamber and a pumping chamber separated by said pumping diaphragm, one-way valves serving said pumping chamber, a rod in said spring chamber and connected to said diaphragm, sealing means between said body and said rod and in a plane normal to said rod, spring means in said spring chamber and adapted to cooperate with said rod for actuating said diaphragm, and a vent channel extending through the wall of said spring chamber with inside and outside ends of the channel angularly spaced about the axis of the pump diaphragm and in said plane.

2. A pump having a pumping diaphragm and a body, a spring and pumping chambers enclosed in said body and separated by said pumping diaphragm, one-way valve means adapted to control flow through said pumping chamber, a rod in said spring chamber and having one end connected to said diaphragm, sealing means between said body and said rod and located in a given plane, spring means in said spring chamber and cooperating with said rod for actuating said diaphragm, a vent channel formed in said body, and the said channel having outside and inside openings angularly spaced in said plane about the axis of the said rod whereby said spring chamber is indirectly vented.

3. A pump as set forth in claim 2, said vent channel being defined by said body wall and said sealing means.

4. A pump as set forth in claim 2, said vent channel being arcuate and partially defined by said sealing means.

5. A fuel pump having a body and a pumping diaphragm, a spring chamber and a pumping chamber in said body and separated by said pumping diaphragm, oneway pressure actuated valve means serving said pumping chamber to control flow therethrough, a rod in said spring chamber with one end connected to said diaphragm and the other end being adapted to be exteriorly actuated, annular sealing means fixed in position between said body and said rod and permitting reciprocation of the latter, spring means in said spring chamber and cooperating with said rod for actuating said diaphragm, an annular channel extending around the center line of said rod and defined by said sealing means and pump body, and the said channel being provided with inside and outside openings diametrically opposed with respect to the axis of said rod and diaphragm whereby said spring chamber is vented.

6. A fuel pump having a body, a pumping diaphragm and a sealing diaphragm, said body defining a pumping chamber and a spring chamber separated by said pumping chamber and a spring chamber separated by said pumping diaphragm, one-way pressure actuated valve means serving said pumping chamber to control fiow therethrough, a rod extending through said spring chamber and sealing diaphragm with one end fixed to said pumping diaphragm, a spring in said spring chamber and acting between said sealing and pumping diaphragms to urge said pumping diaphragm toward said pumping chamher, a channel at least partially defined by said body and located between the latter and said sealing diaphragm, inside and outside openings angularly spaced about said rod and connected to said channel, and said inside opening being connected to said spring chamber.

7. A fuel pump as set forth in claim 6, said channel being partially defined by said sealing diaphragm.

8. A pump having a pumping diaphragm, a body defining a pumping chamber and a spring chamber on opposite sides of said pumping diaphragm, valve means adapted to serve said pumping chamber, spring means in said spring chamber urging said pumping diaphragm toward said valve means, a channel within the confines of said body, an outside opening defined by said body and connecting said channel to the atmosphere, an inside opening connecting said spring chamber to said channel, and said outside and inside openings being angularly spaced about the axis of the said pumping diaphragm and located radially outward of said spring means whereby an indirect vent passage for said spring chamber is achieved.

9. A pump as set forth in claim S, said body having a recess on its exterior and into which said outside opening is connected.

10. A fuel pump as set forth in claim 8, a shield interposed between said spring and said sealing diaphragm, and said channel being defined by said body and shield.

References Cited by the Examiner UNITED STATES PATENTS 1/30 Zubaty 103-450 X 5/62 Johnson 103--150 X 

1. A PUMP HAVING A PUMPING DIAPHRAGM AND A BODY ENCLOSING A SPRING CHAMBER AND A PUMPING CHAMBER SEPARATED BY SAID PUMPING DIAPHRAGM, ONE-WAY VALVES SERVING SAID PUMPING CHAMBER, A ROD IN SAID SPRING CHAMBER AND CONNECTED TO SAID DIAPHRAGM, SEALING MEANS BETWEEN SAID BODY AND SAID ROD AND IN A PLANE NORMAL TO SAID ROD, SPRING MEANS IN SAID SPRING CHAMBER AND ADAPTED TO COOPERATE WITH SAID ROD FOR ACTUARTING SAID DIAPHRAGM, AND A VENT CHANNEL EXTENDING THROUGH THE WALL OF SAID SPRING CHAMBER WITH INSIDE AND OUTSIDE ENDS OF THE CHANNEL ANGULARLY SPACED ABOUT THE AXIS OF THE PUMP DIAPHRAGM AND IN SAID PLANE. 